From 7a7a9bd7aceea77dc2397bc58a1e88197ed759cb Mon Sep 17 00:00:00 2001 From: Ilan Tayari Date: Sun, 16 Apr 2017 11:00:07 +0300 Subject: [PATCH] gso: Validate assumption of frag_list segementation Commit 07b26c9454a2 ("gso: Support partial splitting at the frag_list pointer") assumes that all SKBs in a frag_list (except maybe the last one) contain the same amount of GSO payload. This assumption is not always correct, resulting in the following warning message in the log: skb_segment: too many frags For example, mlx5 driver in Striding RQ mode creates some RX SKBs with one frag, and some with 2 frags. After GRO, the frag_list SKBs end up having different amounts of payload. If this frag_list SKB is then forwarded, the aforementioned assumption is violated. Validate the assumption, and fall back to software GSO if it not true. Fixes: 07b26c9454a2 ("gso: Support partial splitting at the frag_list pointer") Signed-off-by: Ilan Tayari Signed-off-by: Ilya Lesokhin Signed-off-by: David S. Miller --- net/core/skbuff.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 5d9a11ea..ad2af56 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -3082,22 +3082,32 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb, if (sg && csum && (mss != GSO_BY_FRAGS)) { if (!(features & NETIF_F_GSO_PARTIAL)) { struct sk_buff *iter; + unsigned int frag_len; if (!list_skb || !net_gso_ok(features, skb_shinfo(head_skb)->gso_type)) goto normal; - /* Split the buffer at the frag_list pointer. - * This is based on the assumption that all - * buffers in the chain excluding the last - * containing the same amount of data. + /* If we get here then all the required + * GSO features except frag_list are supported. + * Try to split the SKB to multiple GSO SKBs + * with no frag_list. + * Currently we can do that only when the buffers don't + * have a linear part and all the buffers except + * the last are of the same length. */ + frag_len = list_skb->len; skb_walk_frags(head_skb, iter) { + if (frag_len != iter->len && iter->next) + goto normal; if (skb_headlen(iter) && !iter->head_frag) goto normal; len -= iter->len; } + + if (len != frag_len) + goto normal; } /* GSO partial only requires that we trim off any excess that -- 2.7.4